Lawmakers voted to make Washington the seventh state to allow gay marriage. Opponents vow to force the measure onto the November ballot, but obtaining a voter veto of the new law will be an uphill battle.

Gov. Chris Gregoire and Rep. Jamie Pedersen embrace after the House voted to legalize gay marriage in Washington State Wednesday at the state capitol in Olympia. Gov. Gregoire is expected to sign the bill next week.

Ashland, Ore. — For supporters of same-sex marriage in the United States, it’s been a good week.

A federal appeals court struck down California’s Prop. 8 measure banning gay marriage. And a day later, Washington became the seventh state to give same-sex couples the right to marry.

The Washington House of Representatives voted 55 to 43 Wednesday to approve gay marriage. The State Senate already had passed the measure 28 to 21, and Gov. Chris Gregoire (D), who calls it “a major step toward completing a long and important journey to end discrimination based on sexual orientation,” will sign the bill.

The history of the Washington State bill mirrors the shift in public and political attitudes toward gay marriage around the country.

In 1998, state lawmakers passed a Defense of Marriage Act declaring marriage to be a union between a man and a woman. In 2006, a state civil rights measure specifically including protections based on sexual orientation passed for the first time. The next year, a domestic partnership law was enacted, and in 2009 voters approved expanding that law to include everything but marriage.

The new gay marriage law was approved largely along party lines. Just two Republicans voted for it, and two Democrats voted against it. Prominent companies in the Pacific Northwest – including Microsoft, Amazon, and Starbucks – publicly support same-sex marriage and endorsed the bill. (Some conservative Christian organizations launched a boycott of Starbucks as a result.)

But there won’t be an immediate rush to the altar.

The measure takes effect in 90 days, but before then opponents vow to collect the necessary 120,000 signatures to send the question to the voters as a November ballot question. The move would put the new law on hold until the vote.

But the effort to obtain what is, in effect, a voter veto of the new law could be an uphill fight.

A recent University of Washington survey finds increasing support for same-sex marriage. The number of people who say they support gay marriage has increased from 30 percent to 43 percent over the past five years, and another 22 percent say same-sex couples should have exactly the same rights as married couples do today without calling it “marriage.”

If the question is put to voters in the fall, according to the University of Washington poll, 38 percent say they’d vote to overturn the new legislation, but 53 percent would uphold it.

Lawmakers in New Jersey are expected to vote on gay marriage next week (although it faces a threatened veto by Republican Gov. Chris Christie), and Maine could see a gay marriage proposal on the November ballot. In Maryland, Gov. Martin O’Malley (D) called the news from Washington State “yet another step forward for equal protection under the law for all Americans.”

“It is time for Maryland to do the same,” he said.

At the same time, proposed amendments to ban gay marriage will be on the ballots in North Carolina in May and in Minnesota in November.

Washington State’s new law doesn’t require churches and other religious institutions to perform same-sex marriages, and they may refuse to allow their facilities to be used for such weddings. Republicans pushed for a one-month residency requirement as well as exemptions for wedding-related businesses (such as photographers and cake bakers) whose owners might object on moral or religious grounds, but those efforts failed.

Washington Rep. Jamie Pedersen (D), who is gay and in a long-term relationship, spoke of the connection between the federal court ruling in California and Washington State’s new law.

"The court addressed the question of why marriage matters directly," he said, noting that the California ruling called marriage “the name that society gives to the relationship that matters most between two adults."

"I would like for our four children to grow up understanding that their daddy and their poppa have made that kind of a lifelong commitment to each other," he said. "Marriage is the word that we use in our society to convey that idea."